Method for controlling temperature of multi-zone heating furnace

Abstract

This invention relates to a method of controlling the temperature of a heating furnace which has at least one furnace zone capable of being controlled by heating means and which conveys materials to be heated, that are introduced thereinto, by conveyor means such as a walking beam or a pusher so that the materials are heated to a predetermined temperature until they are withdrawn from the discharge side. More specifically, the present invention relates to a method of controlling set furnace zone temperature of the heating furnace when the materials to be heated, that are introduced into the heating furnace, have different temperature elevation patterns. The method of the invention is specifically characterized in that the predetermined set temperatures of each zone is used when the temperature elevation patterns of slabs are different with each other. The invention is directed to minimize the idle time inside the furnace when the materials having different temperature elevation patterns are sequentially introduced into the furnace, in order to conserve energy. The method is especially effective when the cold and hot materials are introduced into the furnace.

What is claimed is: 
     
       1. In a method of controlling the temperature inside a heating furnace having at least one furnace zone capable of being controlled by heating means and while conveying and heating therein materials to be heated that are introduced thereinto, withdrawing said materials to be heated after they are heated to a predetermined temperature, a method of controlling the temperature of a heating furnace comprising: memorizing sequentially specific data of said materials to be rolled that are introduced into said heating furnace;   shifting and memorizing said memory values in accordance with the conveying operation of conveyor means inside said heating furnace;   setting a furnace zone temperature in accordance with movement of said materials to be heated;   attaining said furnace zone temperatures set in the preceding temperature setting step by controlling the furnace zone temperatures with said heating means of said furnace zones;   changing the set temperature of said furnace zones in accordance with the position of a leading boundary material of plural materials having different temperature elevation patterns from those of said plural materials to be heated that are sequentially introduced; and   attaining the changed furnace zone temperatures set in the preceding temperature set changing step by controlling the furnace zone temperatures with said heating means of said furnace zones.   
     
     
       2. The method of controlling a temperature of a heating furnace as defined in claim 1, wherein the set temperature of said furnace zone is changed in the set temperature changing step to such values as are suited for plural materials to be heated, including said boundary material to be heated, when said boundary material enters said furnace zones. 
     
     
       3. The method of controlling a temperature of a heating furnace as defined in claim 1, wherein the set temperatures of said furnace zones are changed in the set temperature changing step to such values as suited for plural materials to be heated subsequent to said boundary material to be heated, before said boundary material enters said furnace zones. 
     
     
       4. The method of controlling a temperature of a heating furnace as defined in claim 3, wherein the set temperatures of said furnace zones are changed in the set temperature changing step to such values as suited for plural materials to be heated subsequent to said boundary material to be heated, in advance by a predetermined period of time before said boundary material enters said furnace zones. 
     
     
       5. The method of controlling a temperature of a heating furnace as defined in claim 3, wherein the set temperatures of said furnace zones are changed in the set temperature changing step to such values as are suited for plural materials to be heated subsequent to said boundary material to be heated, in advance by a heat response time of said furnace zones before said boundary material enters said furnace zones. 
     
     
       6. The method of controlling a temperature of a heating furnace as defined in claim 3, wherein the set temperatures of said furnace zones are changed in the set temperature changing step to such values as suited for plural material to be heated, in advance by a 90% heat response time of said furnace zones before said boundary material enters said furnace zones. 
     
     
       7. The method of controlling a temperature of a heating furnace as defined in claim 3, wherein the set temperatures of said furnace zones are changed during the set temperature changing step to such values as suited for plural materials to be heated subsequent to said boundary material to be heated, in advance by a 63% heat response time of said furnace zones before said boundary material enters said furnace zones. 
     
     
       8. The method of controlling a temperature of a heating furnace as defined in claim 1, wherein the changed value of the temperature set is released when a difference signal between the changed set furnace temperature and the measured furnace temperature becomes smaller than a predetermined value, and thereafter steady temperature control on the basis of said temperature elevation patterns is resumed. 
     
     
       9. The method of controlling a temperature of a heating furnace as defined in claim 1, wherein the changed value of the temperature set is release after the passage of response time of said furnace zones from the set time of the change, and thereafter the steady temperature control on the basis of said temperature elevation patterns is resumed. 
     
     
       10. The method of controlling a temperature of a heating furnace as defined in claim 1, wherein the plural materials to be heated have at least one hot material and one cold material. 
     
     
       11. The method of controlling of a heating furnace according to claim 1, wherein the step of changing the set temperature in accordance with the position of a leading boundary material is performed based upon information obtained by tracking the location of said boundary material.